fix(model-selector): match colon-prefixed names

[marius-kilocode]

Model names with a colon-separated provider prefix, such as SpaceXAI: Grok 4.20, are displayed correctly but the VS Code model selector removes that prefix before ranking search results. Searching for SpaceX therefore returns no result.

Keep the sanitized full display name as a searchable field while preserving the existing prefix-stripped matching used for model names. Add regression coverage for the VS Code selector and CLI picker.

The change is limited to model search ranking and does not alter model display or selection behavior.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Files Reviewed (4 files)

• .changeset/model-selector-provider-prefix.md
• packages/kilo-vscode/tests/unit/model-selector-utils.test.ts
• packages/kilo-vscode/webview-ui/src/components/shared/model-selector-utils.ts
• packages/tui/test/kilocode/model-picker.test.ts

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_{Reviewed by grok-4.6 · Input: 77.8K · Output: 8.5K · Cached: 264.2K}

_{Review guidance: REVIEW.md from base branch main}